Amelanchier arborea (Shadbush, Shadberry)
Amelanchier arborea - shadbush, shadberry, common serviceberry (Rosaceae)
The species Amelanchier arborea is divided into three varieties (9). The full name of the variety found in the North Woods is "Amelanchier arborea var. arborea (Michx. f.) Fernald" (9). The common name "shadbush" was coined because the species' flowering often coincides with the time of the upriver migration of the shad fish. This species is also called the common serviceberry, a name derived from the Sarvis tree (8).
A. arborea grows as a large shrub or a small undestory tree with a maximum height at maturity of 10 meters (8). It is slow-growing but is an early successional species in the American Midwest (5b). It does not have one dominant central trunk extending to the top of the tree, but rather, it has many branches that together compose the tree's general shape (5). The bark of the tree is thin, smooth and gray, sometimes showing vertical stripes, and the twigs are red-brown to purplish-gray (12). It can be distinguished by its clusters of white, 5-petaled flowers. Before flowering, the buds can be 10-12mm in length, coming to a point at the end, and at least part is usually red (12). A. arborea has an alternate, simple leafing arrangement (8, 4). (For visual representations of some of the following leaf morphology characteristics please click here.) The leaves are between one and three inches long, ovate (egg-shaped) to obovate (inverted-egg-shaped), acute to acuminate, with the leaf base rounded to cordate (heart-shaped), and with serrate margins (1, 8). The undersides of the leaves are pubescent (covered in fine, soft hairs) when young, but this diminishes as the plant matures (1). The pubescence helps the plant to keep warmth near the leaves in cold temperatures (5b). The petiole ranges from 3/8" to 1.5" (1).
Habitat and Range:
A. arborea tends to be located in areas of sun or partial shade (2). It is most successful in soils with a pH between 5.5 and 7.5, and it is not tolerant of calcium carbonate. Its success in the North Woods is interesting in this regard, given the presence of carbonate-containing bedrock underlying the North Woods (13). The North Woods lies primarily on limestones and dolostones of the Gailor and Hoyt Formations (13) (see Geology of the North Woods). A. arborea is commonly found on slopes and in rocky forest, along forest edges and along stream banks (8, 5, 2). The species is native to the eastern half of the United States and Canada (9).
The flowers have petals 10-14mm long, and they grow in drooping clusters (racemes) at the tips of the branches (4). In the North Woods, they bloom during mid-late April, before the leaves appear on the tree (10), and they only bloom for 4-7 days. They bloom synchronously (at the same time), with 90% of the flowers of a tree blooming within 2-5 days (5a). This species is pollinated by small bees, most of which are members of the families Andrenidae and Halictidae. Bees are often the first pollinators to become active in the spring. However, other pollinators of this species include other member of the order Hymenoptera, Diptera, and Coleoptera (5a). The pendulous nature of the flower and its white color indicates that it might also be pollinated by bats. It is hermaphroditic (2), which means that each flower contains both male and female reproductive parts. Not only does A. arborea regenerate from seed, but it also sprouts from its roots (8, 10). This is especially common during regeneration after fire (10).
The 1/4 - 1/3 inch diameter apple-shaped fruits become ripe by June-July (1, 10, 5b). They are red-purple, becoming more purple as they ripen. The fruits are edible and often have a very sweet taste similar to that of a blueberry. At maturity, each fruit can contain between five and ten seeds, but most have ten seeds (5a). The number of seeds per fruit influences timing of fruit ripening, which causes asynchronous ripening. One study showed that the number of seeds per fruit did not correlate significantly with availability of mineral or photosynthate resources, or pollen, both of which are common causes for variation (5a).
The fruit attracts over forty species of birds, which aid greatly in its dispersal (8). This also promotes seed germination through seed scarification during the digestion process (8). Dozens of mammal species including squirrels, chipmunks, mice, foxes, black bears, and elk may disperse the seeds (8), but rodents may also act as seed predators (5a). In the North Woods, the most likely mammal dispersers are squirrels, chipmunks, and mice.
Defenses and natural enemies:
Rabbits have been found to eat and destroy A. arborea seedlings. Cambium miners often invade the tree and make light vertical lines in the trunks, but they are not fatal to the tree (5). A. arborea are also prone to parasitism by leaf miners (5). Leaves can be skeletonized by insects such as the pear sawfly, so that parts of the leaf are completely removed by insects continuously scraping off the outside of the leaves (5). Borers can invade the tree, but healthy trees are less prone to attack (5). Spider mites may feed on A. arborea and cause loss of green coloring in the leaves, and they may leave very fine webs (5). Gypsy moths specialize on Amelanchier arborea, as well (10). Finally, aphids can invade to suck liquids from inside the leaves, and cause disruption of tree growth (5). They deposit honeydew on the lower leaves of the tree, which becomes covered in an indicative black mold (5).
In addition to insects, diseases such as Witch's Broom can attack A. arborea (5). Witch's Broom causes the apical part of the tree to branch into several shoots, and coats this area with a black fungus (5). Leaf blight can cause dark brown-purple spots on leaves, and cause leaves to drop (5). Fire blight causes the death of branch tips, and is indicated by the wilting and blackening of the flowers on the branch (5).
Reference Individuals in the North Woods:
Two shrubby individuals can be found on the perimeter of Skidmore "North Lot" parking lot, near the edge of the North Woods. One can be seen to the left immediately upon entering the parking lot, and the second is to the left further along the lot's perimeter. This second individual shows evidence of damage. These individuals were in flower on April 26th, 2008. Representatives of A. arborea can also be found in the North Woods at trail marker #10 (13), which can be reached by taking a left on the red trail from the North Lot entrance. These individuals were not flowering on April 26th, and it is suspected that they had not yet flowered for the season by that date. This could be a result of the denser canopy cover above them; the flowering individuals were located in areas of full or almost full sunlight. Additionally, April 26th fell at the end of a period of about three weeks during which the North Woods received very little rain. This is unusual for the area; April is ordinarily one of the months with the greatest amount of rainfall. This lack of moisture may have delayed flowering on some members of the species.
A. arborea has an extensive root network and can be used to help stabilize slopes (2). It was also used by Native Americans for medicinal purposes (6), and the berries were used in making breads and other foods (4). The wood of this species is one of the densest in North America (5b).
(1) "Amelanchier arborea Michx." hort.net Mallorn Computing, Inc. <http://www.hort.net/profile/ros/amear/> Accessed 6 Apr. 2008.
(2) "Amelanchier arborea-(Michx f.)Fernald." Plants for a future. <http://www.pfaf.org/database/plants.php?Amelanchier+arborea> Accessed 6 Apr. 2008.
(3) Cook, W. 31 Mar. 2008. "Common serviceberry (Amelanchier arborea)." <http://www.duke.edu/~cwcook/trees/amar.html> Accessed 7 Apr. 2008.
(4) Fernald, M. L. et al. 1958. Edible wild plants of eastern North America. Harper and Brothers, New York.
(5) Gilman, E. F. and D. G. Watson. Nov. 1993. "Amelanchier arborea: Downy serviceberry." Fact Sheet ST-73. Environmental Horticulture Department. University of Florida.
(5a) Gorchov, D. 1988. Effects of pollen and resources on seed number and other fitness components in Amelanchier arborea (Rosaceae: Maloideae). American Journal of Botany 75(9). 1275-1285.
(5b) Gregg, K. et al. 2001. Spirit in nature: a handbook. Middlebury College, Vermont.
(6) Moerman, D. "Native American ethnobotany." University of Michigan. <http://herb.umd.umich.edu/> Accessed 6 Apr. 2008.
(7) "Native Plant Database: Amelanchier arborea." 2 Sept. 2007. Ladybird Johnson Wildflower Center. University of Texas at Austin. <http://www.wildflower.org/plants/result.php?id_plant=AMAR3> Accessed 12 Apr. 2008.
(8) "Plant Guide." USDA Natural Resources Conservation Service National Plant Data Center & Biota of North America Program. <http://plants.usda.gov/plantguide/pdf/pg_amar3.pdf> Accessed 6 Apr. 2008.
(9) "PLANTS Profile: Amelanchier arborea (Michx. f.)Fernald Common serviceberry." USDA Natural Resources Conservation Service. <http://plants.usda.gov/java/profile?symbol=AMAR3> Accessed 5 Apr. 2008.
(10) "Species: Amelanchier arborea." Fire Effects Information System. USDA Forest Service. <http://www.fs.fed.us/database/feis/plants/tree/amearb/all.html#DISTRIBUTION%20AND%20OCCURRENCE> Accessed 10 Apr. 2008.
(11) "Taxon: Amelanchier Arborea." Germplasm Resources Information Network. USDA Agricultural Research Service. <http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?2871> Accessed 10 Apr. 2008.
(12) "Trees of Wisconsin." Herbarium Cofrin Center for Biodiversity. University of Wisconsin. <http://www.uwgb.edu/biodiversity/herbarium/trees/amearb01.htm> Accessed 7 Apr. 2008.
(13) Van Hook, S. 2007. Treasure in the North Woods. Digital Page, Albany, NY.